Display device

ABSTRACT

A display device is disclosed, which comprises: a first substrate; a first metal layer disposed on a surface of the first substrate; a first insulating layer disposed on the first metal layer; a second insulating layer disposed on the first insulating layer; and a second metal layer covering a part of the second insulating layer and comprising a connecting region, wherein the first metal layer and the second metal layer are electrically connected to each other in the connecting region, wherein the second metal layer corresponding to the connecting region comprises a sidewall region and a non-sidewall region, a first thickness of the sidewall region corresponding to the second insulating layer along a direction parallel to the surface of the first substrate is smaller than a second thickness of the non-sidewall region along a direction perpendicular to the surface of the first substrate.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/572,460, filed Dec. 16, 2014, which claims the priority of TaiwanPatent Application Serial Number 103116212, filed on May 7, 2014, thesubject matter of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device and, moreparticularly, to a display device capable of decreasing resistance,reducing current leakage, improving capacity value and increasingstorage capacity in pixels.

2. Description of Related Art

In recent years, all the display devices are developed toward havingsmall volume, thin thickness and light weight as the display techniquesprogresses. Hence, a conventional cathode ray tube (CRT) display isgradually replaced by flat panel display devices such as a liquidcrystal display (LCD) device and an organic light emitting diode (OLED)display device. The flat panel display devices can be applied to variousfields. For example, the daily used devices such as cell phones,notebooks, video cameras, cameras, music players, navigation devices,and televisions are equipped with the flat panel display devices.

Although the LCD device and the OLED display device are commerciallyavailable and especially the techniques for the LCD device are muchmature, every manufacturer is desired to develop display devices withimproved display quality to meet customers' requirement as the displaydevices developed. In particular, the OLED display device is oneimportant target for manufacturers.

Even though the LCD device and the OLED display device are welldeveloped and commercialized, it is still necessary to develop a displaydevice with improved display quality to meet the customers' requirement.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a display panel todecrease resistance, reduce current leakage, improve capacity value andincrease storage capacity in pixels.

To achieve the object, the present invention provides a display device,comprising: a first substrate; a first insulating layer disposed on thefirst substrate; a second insulating layer disposed on the firstinsulating layer; and a metal layer disposed on the second insulatinglayer and comprising plural conductive lines, wherein an opening regionis located between two adjacent conductive lines to expose the secondinsulating layer, wherein a thickness of the second insulating layerunder the metal layer is larger than that exposed from the openingregion. More specifically, the metal layer of the present invention is apatterned metal layer, and the thickness of the second insulating layerunder the conductive lines of the patterned metal layer is larger thanthat exposed from the opening region.

In other words, the present invention provides a display device,comprising: a first substrate; a first insulating layer disposed on thefirst substrate; a second insulating layer disposed on the firstinsulating layer; and a metal layer covering a part of the secondinsulating layer, wherein a thickness of the second insulating layerunder the metal layer (i.e. covered with the metal layer) is larger thanthat uncovered with the metal layer.

In the display device of the present invention, the thickness of thesecond insulating layer covered with the metal layer is increased toachieve the purpose of decreasing resistance and reducing currentleakage. Meanwhile, the thickness thereof uncovered with the metal layerand exposed from the opening region is decreased to achieve the purposeof improving capacity value and increasing storage capacity in pixels.

In the display panel of the present invention, the thickness of thesecond insulating layer exposed from the opening region (i.e. uncoveredwith the metal layer) is smaller than that under the metal layer(especially, the conductive lines of the metal layer). The thickness ofthe second insulating layer exposed from the opening region ispreferably 10˜95%, more preferably 20˜80%, and most preferably 25%˜35%of that under the conductive lines.

In addition, in the display panel of the present invention, the firstinsulating layer and the second insulating layer can be made of anydielectric material generally used in the art, such as silicon oxide andsilicon nitride. Preferably, the first insulating layer is a siliconoxide layer; and/or the second insulating layer is a silicon nitridelayer.

Furthermore, in the display panel of the present invention, an undercutis present in the first insulating layer under the second insulatinglayer. More specifically, the first insulating layer comprises a firstside wall, the second insulating layer comprises a second side wall, andthe second side wall is protruded beyond the first side wall.

In the display panel of the present invention, a sealant may be furtherdisposed on the first substrate, and the thickness of the secondinsulating layer under the conductive lines of the patterned metal layeris larger than that under the sealant. Herein, the material for thesealant can be selected based on the types of the display panel. In onecase that the display device of the present invention is a liquidcrystal display (LCD) device, a frame sealant known in the art can beused as the sealant. In another case that the display device is anorganic light emitting diode (OLED) display device, a frit sealant knownin the art can be used as the sealant, which has excellent moisturebarrier property and air impermeability.

The display device of the present invention can be applied as an OLEDdisplay device or a LCD device. In the case that the display device ofthe present invention is an OLED display device, the device may furthercomprise a planer layer disposed on the metal layer (especially, theconductive lines of the patterned metal layer) and in the opening regionuncovered with the metal layer; additionally, the device may furthercomprise an organic light emitting diode unit, which comprises a firstelectrode, a second electrode and an organic light emitting layerdisposed therebetween, wherein the metal layer (i.e. the conductivelines of the patterned metal layer) is electrically connected to thefirst electrode.

Furthermore, in the case that the display device of the presentinvention is a LCD device, the device may further comprise a liquidcrystal display unit, which comprises a first electrode, a secondelectrode and a liquid crystal layer disposed therebetween, wherein themetal layer (i.e. the conductive lines of the patterned metal layer) iselectrically connected to the first electrode.

Other objects, advantages, and novel features of the invention willbecome more apparent from the following detailed description when takenin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an OLED display device according toEmbodiment 1 of the present invention;

FIG. 2 is a perspective view showing a layout of an OLED display deviceaccording to Embodiment 1 of the present invention;

FIG. 3 is a cross-sectional view showing a part of a display region ofan OLED display device according to Embodiment 1 of the presentinvention;

FIGS. 4A and 4B are respectively cross-sectional views showing parts ofan OLED display device according to Embodiment 1 of the presentinvention;

FIG. 5 is a perspective view showing a part of a non-display region ofan OLED display device according to Embodiment 1 of the presentinvention;

FIG. 6 is a cross-sectional view of an OLED display device along a P-P′line in FIG. 5 according to Embodiment 1 of the present invention;

FIG. 7 is an enlarged view showing a region E of an OLED display devicein FIG. 3 according to Embodiment 1 of the present invention;

FIG. 8 is a cross-sectional view showing a sealant region of an OLEDdisplay device in FIG. 1 according to Embodiment 1 of the presentinvention;

FIG. 9 is a cross-sectional view of a LCD device according to Embodiment2 of the present invention; and

FIG. 10 is a cross-sectional view showing a part of a display region ofa LCD device according to Embodiment 2 of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention has been described in an illustrative manner, andit is to be understood that the terminology used is intended to be inthe nature of description rather than of limitation. Many modificationsand variations of the present invention are possible in light of theabove teachings. Therefore, it is to be understood that within the scopeof the appended claims, the invention may be practiced otherwise than asspecifically described.

Embodiment 1

FIG. 1 is a cross-sectional view of an OLED display device of thepresent embodiment. During the process for manufacturing the OLEDdisplay device, a first substrate 11 and a second substrate 12 arefirstly provided. Organic light emitting diode (OLED) units 15 and pixeldefining layers 16 are disposed on the first substrate 11, wherein eachpixel defining layer 16 is disposed between two adjacent OLED units 15.In addition, plural spacers 14 are disposed on the second substrate 12,and a sealant 13 (a frit sealant in the present embodiment) is formed ona periphery of the second substrate 12 in advance, which is formedthrough a dispensing process and a sintering process to fix on thesecond substrate 12. Then, the first substrate 11 is assembled with thesecond substrate 12, wherein the spacers 14 on the second substrate 12correspond to regions outside the pixel opening 161 of the pixeldefining layer 16. After the sealant 13 is adhered onto the firstsubstrate 11 through a laser process, an OLED display device of thepresent embodiment is obtained.

In the present embodiment, both the first substrate 11 and the secondsubstrate 12 are glass substrates. In addition, the OLED display deviceof the present embodiment comprises a display region A and a non-displayregion B, which is a region with circuits formed thereon. Furthermore,in the present embodiment, the OLED units 15 can respectively emit red,green and blue light; but the present invention is not limited thereto.For example, the OLED units 15 can be white OLED units, and a colorfilter unit (not shown in the figure) may be further disposed on thesecond substrate 12.

FIG. 2 is a perspective view showing a layout of an OLED display deviceof the present embodiment. As shown in FIG. 2, in the OLED displaydevice of the present embodiment, each pixel unit respectivelycomprises: a scan line, a data line, a capacitor line, a supply line, aswitching thin film transistor unit (shown as switching TFT in FIG. 2),a driving thin film transistor unit (shown as driving TFT in FIG. 2), astorage capacitor, and an OLED unit (shown as OLED in FIG. 2) connectingto a first electrode and a second electrode.

FIG. 3 is a cross-sectional view showing a part of a display region ofan OLED display device of the present embodiment. As shown in FIGS. 1and 3, the OLED display device of the present embodiment comprises: afirst substrate 11 and a second substrate 12 opposite thereto. In thepresent embodiment, the thin film transistor (TFT) units used in theOLED display device are low temperature poly-silicon (LTPS) TFT units.As shown in FIG. 3, in the display region A, a first substrate 11 isfirstly provided, and a silicon nitride buffer layer 101 and a siliconoxide buffer layer 102 are sequentially formed thereon. In the TFT unitregion T, a poly-silicon layer 103 formed by annealing amorphous siliconwith laser is further disposed on the silicon oxide buffer layer 102.Next, a silicon oxide insulating layer 104, a first metal layer 111, agate insulating layer 112 and a Mo layer 111′ are sequentially formed onthe first substrate 11. Herein, the first metal layer 111 in the TFTunit region T is used as a gate electrode. The material for the gateinsulating layer 112 can be any insulating material generally used inthe art, such as silicon oxide. Next, a first insulating layer 114, asecond insulating layer 115 and a second metal layer 116 aresequentially laminated on the gate insulating layer 112 and the Mo metallayer 111′. Herein, the second metal layer 116 in the TFT unit region Tis further penetrated through the gate insulating layer 112, the firstinsulating layer 114 and the second insulating layer 115 to connect tothe poly-silicon layer 103. Finally, a planer layer 117, a firstelectrode 151 and a pixel defining layer 16 are sequentially formedthereon, wherein the first electrode 151 locates not only on the planerlayer 117 but also in a planer layer opening 117 a thereof toelectrically connect to the second metal layer 116, and the pixeldefining layer 16 further has a pixel opening 161.

Herein, the first metal layer 111 and the second metal layer 116 areused as conductive lines. For example, as shown in FIG. 3, the firstmetal layer 111 is used as a gate electrode of the TFT unit, and thesecond metal layer 116 is used as a source and drain electrode of theTFT unit. The second metal layer 116 is a patterned metal layer with anopening region 116 a to expose the second insulating layer 115 under thesecond metal layer 116. In addition, the gate electrode and the scanline formed by the first metal layer 111 electrically connect to eachother, and the source and drain electrode and the data line formed bythe second metal layer 116 also electrically connect to each other. Inthe present embodiment, the material for the first metal layer 111 andthe second metal layer 116 can be any conductive material generally usedin the art, such as metal, alloy, metal oxide, metal oxynitride, orother electrode materials generally used in the art; and preferably ismetal. In the present embodiment, the first metal layer 111 is made ofMo, and the second metal layer 116 is a composite metal layer with a Tilayer, an Al layer and another Ti layer sequentially laminated from aside facing to the first substrate 11.

Not only the LTPS TFT units shown in FIG. 3 but also IGZO TFT units canbe used in the OLED display device of the present embodiment. FIGS. 4Aand 4B are respectively cross-sectional views showing TFT unit regionsof the OLED display device of the present embodiment. As shown in FIG.4A, a first metal layer 111, a gate insulating layer 112, asemiconductor layer 113, a first insulating layer 114, a secondinsulating layer 115 and a second metal layer 116 are sequentiallylaminated on the first substrate 11 to form a TFT unit, wherein thesecond metal layer 116 connects to the semiconductor layer 113. Inaddition, the semiconductor layer 113 is made of IGZO, and the materialsfor the first metal layer 111 and the second metal layer 116 are thesame as those illustrated above. Next, a protection layer 118 with aprotection layer opening 118 a is laminated on the second metal layer116 and in an opening region 116 a thereof, and then a planer layer 117with a planer layer opening 117 a is further laminated on the protectionlayer 118. Herein, the second metal layer 116 is exposed from theprotection layer opening 118 a and the planer layer opening 117 a.

Next, as shown in FIG. 4A, a first electrode 151 is formed on the planerlayer 117 and in the planer layer opening 117 a thereof, and a pixeldefining layer 16 with a pixel opening 161 is sequentially formed on thefirst electrode 151. Then, as shown in FIG. 4B, an organic lightemitting layer 152 and a second electrode 153 are sequentially laminatedon the first electrode 151 and the pixel defining layer 16 and in thepixel opening 161 thereof, to obtain the OLED unit 15 (as shown inFIG. 1) of the present embodiment. Hence, as shown in FIGS. 1 and 4B,the OLED unit 15 of the present embodiment comprises: the firstelectrode 151, a second electrode 153 and an organic light emittinglayer 152 disposed therebetween, wherein the second metal layer 116 iselectrically connected to the first electrode 151. In addition, as shownin FIGS. 4A and 4B, the pixel defining layer 16 locates between thefirst electrode 151 and the organic light emitting layer 152, and alight emitting region is defined by the pixel opening 161 of the pixeldefining layer 16.

For either the LTPS TFT unit shown in FIG. 3 or the IGZO TFT unit shownin FIGS. 4A and 4B, the first insulating layer 114 and the secondinsulating layer 115 can be made of any dielectric material generallyused in the art, such as silicon oxide and silicon nitride. In thepresent embodiment the first insulating layer 114 is a silicon oxidelayer, and the second insulating layer 115 is a silicon nitride layer.

For either the LTPS TFT unit shown in FIG. 3 or the IGZO TFT unit shownin FIGS. 4A and 4B, the first electrode 151 and the second electrode 153can be a transparent electrode or a semi-transparent electrode known inthe art. Herein, the transparent electrode can be a transparentconductive oxide (TCO) electrode, such as an ITO electrode and an IZOelectrode; and the semi-transparent electrode can be a metal thin filmelectrode, such as an Mg/Ag alloy thin film electrode, an Au thin filmelectrode, a Pt thin film electrode and an Al thin film electrode. Inaddition, at least one of the first electrode 151 and the secondelectrode 153 can be a composite electrode of a transparent electrodeand a semi-transparent electrode such as a composite electrode of a TCOelectrode and a Pt thin film electrode, if it is necessary. Herein, onlythe OLED unit comprising the first electrode 151, the organic lightemitting layer 152 and the second electrode 153 are exemplified, but thepresent invention is not limited thereto. Other OLED unit generally usedin the art can also be applied to the OLED display device of the presentinvention, for example, the OLED unit comprising an electrontransporting layer, an electron injection layer, a hole transportinglayer, a hole injection layer, and/or other layers capable offacilitating the combination of holes and electrons.

FIG. 5 is a perspective view showing a part of a non-display region ofthe OLED display device of the present embodiment. As shown in FIGS. 1and 5, in the non-display region, a first metal layer 111, a firstinsulating layer (not shown in the figure), a second insulating layer(not shown in the figure) and a second metal layer 116 are sequentiallylaminated on the first substrate 11, wherein the first metal layer 111and the second metal layer 116 are used as conductive lines, andelectrically connected to each other in a connecting region R1.

FIG. 6 is a cross-sectional view of the OLED display device of thepresent embodiment along a P-P′ line in FIG. 5. As shown in FIG. 6, thefirst metal layer 111 is disposed on the first substrate 11, the firstinsulating layer 114 is disposed on the first metal layer 111, thesecond insulating layer 115 is disposed on the first insulating layer114, and the second metal layer 116 is disposed on the second insulatinglayer 115. Herein, the second metal layer 116 is a patterned metal layerand comprises conductive lines, and an opening region 116 a is locatedbetween two adjacent conductive lines to expose the second insulatinglayer 115, as shown in FIGS. 5 and 6.

FIG. 7 is an enlarged view of the OLED display device of the presentembodiment showing the region E indicated in FIG. 3. As shown in FIG. 7,a thickness T1 of the second insulating layer 115 covered with thesecond metal layer 116 (i.e. the second insulating layer 115 under theconductive lines of the second metal layer 116) is larger than athickness T2 thereof exposed from the opening region 116 a (i.e. thesecond insulating layer 115 uncovered with of the second metal layer116). Preferably, the thickness T2 of the second insulating layer 115exposed from the opening region 116 a is 10˜95% of the thickness T1thereof under the conductive lines of the second metal layer 116. Morepreferably, the thickness T2 is 20˜80% of the thickness T1. Mostpreferably, the thickness T2 is 25˜35% of the thickness T1. In thepresent embodiment, the thickness T2 is 70% less than the thickness T1,i.e. the thickness T2 is 30% of the thickness T1.

Herein, only a part of the OLED display device of the present embodimentis used to illustrate the thickness of the second insulating layer; anda person skilled in the art can understand that the same design for thethickness thereof is also applied onto other parts of the OLED displaydevice.

Furthermore, as shown in FIG. 6, an undercut is present in the firstinsulating layer 114 under the second insulating layer 115. Morespecifically, the first insulating layer 114 comprises a first side wall114 a, the second insulating layer 115 comprises a second side wall 115a, and the second side wall 115 a is protruded beyond the first sidewall 114 a.

FIG. 8 is a cross-sectional view showing a sealant region of the OLEDdisplay device in FIG. 1. In addition, as shown in FIGS. 1 and 8, asealant 13 is further disposed on the first substrate 11. As shown inFIGS. 3, 4A, 4B and 8, the thickness of the second insulating layer 115covered with the second metal layer 116 is larger than that under thesealant 13.

Embodiment 2

FIG. 9 is a cross-sectional view of a LCD device of the presentembodiment. During the process for manufacturing the LCD device, a firstsubstrate 11 and a second substrate 12 are firstly provided, anddifferent units are respectively disposed thereon (not shown in thefigure). For example, in some embodiments, as shown in FIG. 10, TFTunits are disposed on the first substrate 11, and color filter units aredisposed on the second substrate 12 (wherein the color filter units arenot shown in FIG. 10). In other embodiments, both the TFT units and thecolor filter units are disposed on the first substrate 11. In addition,one of the first substrate 11 and the second substrate 12 are disposedwith plural spacers 17, and a sealant 13 (a frame sealant in the presentembodiment) is formed on a periphery of the second substrate 12 inadvance. After the second substrate 12 is assembled with the firstsubstrate 11, a liquid crystal material is injected into the spacebetween the first substrate 11 and the second substrate 12 through anyknown manner used in the art, such as a drop-type injection process oran injection method using a capillary effect, to form a liquid crystallayer 181 to obtain the LCD device of the present embodiment.

FIG. 10 is a cross-sectional view showing a part of a display region ofthe LCD device of the present embodiment. As shown in FIG. 10, in thepresent embodiment, a first metal layer 111, a gate insulating layer112, a first insulating layer 114, a second insulating layer 115, asemiconductor layer 113 and a second metal layer 116 are sequentiallylaminated on the first substrate 11 to form a TFT unit. In addition, aprotection layer 118 is laminated on the second metal layer 116 and inan opening region 116 a thereof. A first electrode 151 is formed on theprotection layer 118, which is electrically connected to the secondmetal layer 116. Herein, the material for the protection layer 118 canbe any known material for the passivation layer such as silicon oxide.Furthermore, in the present embodiment, the thickness of the secondinsulating layer 115 related to the second metal layer 116 is the sameas that illustrated in Embodiment 1, and not described herein.

In addition, as shown in FIG. 10, the LCD device of the presentembodiment comprises: a liquid crystal display unit 18, which comprisesthe first electrode 151, a second electrode 153 and the liquid crystallayer 181 disposed therebetween, wherein the second metal layer 116 iselectrically connected to the first electrode 151. Furthermore, in thepresent embodiment, the second electrode 153 is disposed on the secondsubstrate 12, and a color filter unit (not shown in the figure) isfurther disposed on the second substrate 12.

Moreover, the LCD device of the present embodiment may further comprisea backlight module disposed under the first substrate 11 to provide anincident light to the liquid crystal layer 181.

In conclusion, in the display devices provided by the present invention,the thickness of the second insulating layer covered with the metallayer (which is the second metal layer illustrated in the aforementionedembodiments) to achieve the purpose of decreasing resistance andreducing current leakage. Meanwhile, the thickness thereof exposed fromthe opening region (which is the opening region without covering withthe second metal layer illustrated in the aforementioned embodiments) isdecreased to achieve the purpose of improving capacity value andincreasing storage capacity in pixels. Therefore, the display quality ofthe display device can be improved to meet the customer's requirementfor electronic products.

Furthermore, the display device provided by the present invention can beapplied to any electronic device for displaying images, such as a mobilephone, a notebook, a camera, a video camera, a music player, anavigation system, or a television.

Although the present invention has been explained in relation to itspreferred embodiment, it is to be understood that many other possiblemodifications and variations can be made without departing from thespirit and scope of the invention as hereinafter claimed.

What is claimed is:
 1. A display device, comprising: a first substrate;a first metal layer disposed on a surface of the first substrate; afirst insulating layer disposed on the first metal layer; a secondinsulating layer disposed on the first insulating layer; and a secondmetal layer covering a part of the second insulating layer andcomprising a connecting region, wherein the first metal layer and thesecond metal layer are electrically connected to each other in theconnecting region, wherein the second metal layer corresponding to theconnecting region comprises a sidewall region and a non-sidewall region,the sidewall region corresponding to the second insulating layer has afirst thickness along a direction parallel to the surface of the firstsubstrate, and the non-sidewall region has a second thickness along adirection perpendicular to the surface of the first substrate, whereinthe first thickness is smaller than the second thickness.
 2. The displaydevice as claimed in claim 1, wherein a thickness of the secondinsulating layer under the second metal layer is larger than thatuncovered with the second metal layer.
 3. The display device as claimedin claim 1, wherein the thickness of the second insulating layeruncovered with the second metal layer is 10˜95% of that under the secondmetal layer.
 4. The display device as claimed in claim 1, furthercomprising a first electrode, a second electrode and an organic lightemitting layer disposed between the first electrode and the secondelectrode, wherein the first electrode electrically connecting to thesecond metal layer.
 5. The display device as claimed in claim 4, furthercomprising a pixel defining layer disposed between the first electrodeand the organic light emitting layer, wherein the pixel defining layerhas a pixel opening, and a light emitting region is defined by the pixelopening
 6. The display device as claimed in claim 1, wherein the firstinsulating layer comprises a first side wall, the second insulatinglayer comprises a second side wall, and at least a part of the secondside wall is protruded beyond a part of the first side wall.
 7. Thedisplay device as claimed in claim 1, wherein the display device is anorganic light emitting diode display device or a liquid crystal displaydevice.
 8. A display device, comprising: a first substrate; apoly-silicon layer disposed on the first substrate; a first metal layerdisposed on the poly-silicon layer; a first insulating layer disposed onthe first metal layer; a second insulating layer disposed on the firstinsulating layer; a second metal layer covering a part of the secondinsulating layer; and a planer layer disposed on the second metal layer,wherein a third thickness of the planer layer above the poly-siliconlayer is smaller than a fourth thickness of the planer layer above aregion adjacent to the poly-silicon layer.
 9. The display device asclaimed in claim 8, wherein a thickness of the second insulating layerunder the second metal layer is larger than that uncovered with thesecond metal layer.
 10. The display device as claimed in claim 8,wherein the thickness of the second insulating layer uncovered with thesecond metal layer is 10˜95% of that under the second metal layer. 11.The display device as claimed in claim 8, further comprising a firstelectrode, a second electrode and an organic light emitting layerdisposed between the first electrode and the second electrode, whereinthe first electrode electrically connecting to the second metal layer.12. The display device as claimed in claim 11, further comprising apixel defining layer disposed between the first electrode and theorganic light emitting layer, wherein the pixel defining layer has apixel opening, and a light emitting region is defined by the pixelopening.
 13. The display device as claimed in claim 8, wherein the firstinsulating layer comprises a first side wall, the second insulatinglayer comprises a second side wall, and at least a part of the secondside wall is protruded beyond a part of the first side wall.
 14. Thedisplay device as claimed in claim 8, wherein the display device is anorganic light emitting diode display device or a liquid crystal displaydevice.
 15. A display device, comprising: a first substrate; a firstmetal layer disposed on the first substrate; a semiconductor layerdisposed on the first metal layer; a first insulating layer disposed onthe semiconductor layer; a second insulating layer disposed on the firstinsulating layer; a second metal layer covering a part of the secondinsulating layer; and a planer layer disposed on the second metal layer,wherein a third thickness of the planer layer above the semiconductorlayer is smaller than a fourth thickness of the planer layer above aregion adjacent to the semiconductor layer.
 16. The display device asclaimed in claim 15, wherein a thickness of the second insulating layerunder the second metal layer is larger than that uncovered with thesecond metal layer.
 17. The display device as claimed in claim 15,wherein the thickness of the second insulating layer uncovered with thesecond metal layer is 10˜95% of that under the second metal layer. 18.The display device as claimed in claim 15, further comprising a firstelectrode, a second electrode and an organic light emitting layerdisposed between the first electrode and the second electrode, wherein apixel defining layer is disposed between the first electrode and theorganic light emitting layer, the first electrode electrically connectsto the second metal layer, the pixel defining layer has a pixel opening,and a light emitting region is defined by the pixel opening.
 19. Thedisplay device as claimed in claim 15, wherein the first insulatinglayer comprises a first side wall, the second insulating layer comprisesa second side wall, and at least a part of the second side wall isprotruded beyond a part of the first side wall.
 20. The display deviceas claimed in claim 15, wherein the display device is an organic lightemitting diode display device or a liquid crystal display device.